/*
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Adam Dunkels <adam@sics.se>
 *
 */


/* inet.c
 *
 * Functions common to all TCP/IP modules, such as the Internet checksum and the
 * byte order functions.
 *
 */


#include "lwip/opt.h"

#include "lwip/arch.h"

#include "lwip/def.h"
#include "lwip/inet.h"

#include "lwip/sys.h"

/* This is a reference implementation of the checksum algorithm, with the
 * aim of being simple, correct and fully portable. Checksumming is the
 * first thing you would want to optimize for your platform. You will
 * need to port it to your architecture and in your sys_arch.h:
 *
 * #define LWIP_CHKSUM <your_checksum_routine>
*/
#ifndef LWIP_CHKSUM
#define LWIP_CHKSUM lwip_standard_chksum

/**
 * lwip checksum
 *
 * @param dataptr points to start of data to be summed at any boundary
 * @param len length of data to be summed
 * @return host order (!) lwip checksum (non-inverted Internet sum)
 *
 * @note accumulator size limits summable lenght to 64k
 * @note host endianess is irrelevant (p3 RFC1071)
 */
static u16_t lwip_standard_chksum(void *dataptr, u16_t len)
{
        u32_t acc;
        u16_t src;
        u8_t *octetptr;

        acc = 0;
        /* dataptr may be at odd or even addresses */
        octetptr = (u8_t*)dataptr;
        while (len > 1) {
                /* declare first octet as most significant
                   thus assume network order, ignoring host order */
                src = (*octetptr) << 8;
                octetptr++;
                /* declare second octet as least significant */
                src |= (*octetptr);
                octetptr++;
                acc += src;
                len -= 2;
        }
        if (len > 0) {
                /* accumulate remaining octet */
                src = (*octetptr) << 8;
                acc += src;
        }
        /* add deferred carry bits */
        acc = (acc >> 16) + (acc & 0x0000ffffUL);
        if ((acc & 0xffff0000) != 0) {
                acc = (acc >> 16) + (acc & 0x0000ffffUL);
        }
        /* This maybe a little confusing: reorder sum using htons()
           instead of ntohs() since it has a little less call overhead.
           The caller must invert bits for Internet sum ! */
        return htons((u16_t)acc);
}

#endif

#if 0
/*
 * Curt McDowell
 * Broadcom Corp.
 * csm@broadcom.com
 *
 * IP checksum two bytes at a time with support for
 * unaligned buffer.
 * Works for len up to and including 0x20000.
 * by Curt McDowell, Broadcom Corp. 12/08/2005
 */

static u16_t lwip_standard_chksum2(void *dataptr, int len)
{
        u8_t *pb = dataptr;
        u16_t *ps, t = 0;
        u32_t sum = 0;
        int odd = ((u32_t)pb & 1);

        /* Get aligned to u16_t */
        if (odd && len > 0) {
                ((u8_t *)&t)[1] = *pb++;
                len--;
        }

        /* Add the bulk of the data */
        ps = (u16_t *)pb;
        while (len > 1) {
                sum += *ps++;
                len -= 2;
        }

        /* Consume left-over byte, if any */
        if (len > 0)
                ((u8_t *)&t)[0] = *(u8_t *)ps;
        ;

        /* Add end bytes */
        sum += t;

        /*  Fold 32-bit sum to 16 bits */
        while (sum >> 16)
                sum = (sum & 0xffff) + (sum >> 16);

        /* Swap if alignment was odd */
        if (odd)
                sum = ((sum & 0xff) << 8) | ((sum & 0xff00) >> 8);

        return sum;
}

/**
 * An optimized checksum routine. Basically, it uses loop-unrolling on
 * the checksum loop, treating the head and tail bytes specially, whereas
 * the inner loop acts on 8 bytes at a time.
 *
 * @arg start of buffer to be checksummed. May be an odd byte address.
 * @len number of bytes in the buffer to be checksummed.
 *
 * @todo First argument type conflicts with generic checksum routine.
 *
 * by Curt McDowell, Broadcom Corp. December 8th, 2005
 */

static u16_t lwip_standard_chksum4(u8_t *pb, int len)
{
        u16_t *ps, t = 0;
        u32_t *pl;
        u32_t sum = 0, tmp;
        /* starts at odd byte address? */
        int odd = ((u32_t)pb & 1);

        if (odd && len > 0) {
                ((u8_t *)&t)[1] = *pb++;
                len--;
        }

        ps = (u16_t *)pb;

        if (((u32_t)ps & 3) && len > 1) {
                sum += *ps++;
                len -= 2;
        }

        pl = (u32_t *)ps;

        while (len > 7)  {
                tmp = sum + *pl++;          /* ping */
                if (tmp < sum)
                        tmp++;                    /* add back carry */

                sum = tmp + *pl++;          /* pong */
                if (sum < tmp)
                        sum++;                    /* add back carry */

                len -= 8;
        }

        /* make room in upper bits */
        sum = (sum >> 16) + (sum & 0xffff);

        ps = (u16_t *)pl;

        /* 16-bit aligned word remaining? */
        while (len > 1) {
                sum += *ps++;
                len -= 2;
        }

        /* dangling tail byte remaining? */
        if (len > 0)                  /* include odd byte */
                ((u8_t *)&t)[0] = *(u8_t *)ps;

        sum += t;                     /* add end bytes */

        while (sum >> 16)             /* combine halves */
                sum = (sum >> 16) + (sum & 0xffff);

        if (odd)
                sum = ((sum & 0xff) << 8) | ((sum & 0xff00) >> 8);

        return sum;
}
#endif

/* inet_chksum_pseudo:
 *
 * Calculates the pseudo Internet checksum used by TCP and UDP for a pbuf chain.
 */

u16_t inet_chksum_pseudo(struct pbuf *p,
                   struct ip_addr *src, struct ip_addr *dest,
                   u8_t proto, u16_t proto_len)
{
        u32_t acc;
        struct pbuf *q;
        u8_t swapped;

        acc = 0;
        swapped = 0;
        /* iterate through all pbuf in chain */
        for (q = p; q != NULL; q = q->next)
        {
                LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): checksumming pbuf %p (has next %p) \n",
                                         (void *)q, (void *)q->next));
                acc += LWIP_CHKSUM(q->payload, q->len);
                /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): unwrapped lwip_chksum()=%"X32_F" \n", acc));*/
                while (acc >> 16) {
                        acc = (acc & 0xffffUL) + (acc >> 16);
                }
                if (q->len % 2 != 0) {
                        swapped = 1 - swapped;
                        acc = ((acc & 0xff) << 8) | ((acc & 0xff00UL) >> 8);
                }
                /*LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): wrapped lwip_chksum()=%"X32_F" \n", acc));*/
        }

        if (swapped)
        {
                acc = ((acc & 0xff) << 8) | ((acc & 0xff00UL) >> 8);
        }
        acc += (src->addr & 0xffffUL);
        acc += ((src->addr >> 16) & 0xffffUL);
        acc += (dest->addr & 0xffffUL);
        acc += ((dest->addr >> 16) & 0xffffUL);
        acc += (u32_t)htons((u16_t)proto);
        acc += (u32_t)htons(proto_len);

        while (acc >> 16)
        {
                acc = (acc & 0xffffUL) + (acc >> 16);
        }
        LWIP_DEBUGF(INET_DEBUG, ("inet_chksum_pseudo(): pbuf chain lwip_chksum()=%"X32_F"\n", acc));
        return (u16_t)~(acc & 0xffffUL);
}

/* inet_chksum:
 *
 * Calculates the Internet checksum over a portion of memory. Used primarely for IP
 * and ICMP.
 */

u16_t inet_chksum(void *dataptr, u16_t len)
{
        u32_t acc;

        acc = LWIP_CHKSUM(dataptr, len);
        while (acc >> 16) {
                acc = (acc & 0xffff) + (acc >> 16);
        }
        return (u16_t)~(acc & 0xffff);
}

u16_t inet_chksum_pbuf(struct pbuf *p)
{
        u32_t acc;
        struct pbuf *q;
        u8_t swapped;

        acc = 0;
        swapped = 0;
        for (q = p; q != NULL; q = q->next)
        {
                acc += LWIP_CHKSUM(q->payload, q->len);
                while (acc >> 16) {
                        acc = (acc & 0xffffUL) + (acc >> 16);
                }
                if (q->len % 2 != 0) {
                        swapped = 1 - swapped;
                        acc = (acc & 0x00ffUL << 8) | (acc & 0xff00UL >> 8);
                }
        }

        if (swapped)
        {
                acc = ((acc & 0x00ffUL) << 8) | ((acc & 0xff00UL) >> 8);
        }
        return (u16_t)~(acc & 0xffffUL);
}

/* Here for now until needed in other places in lwIP */
#ifndef isascii
#define in_range(c, lo, up)  ((u8_t)c >= lo && (u8_t)c <= up)
#define isascii(c)           in_range(c, 0x20, 0x7f)
#define isdigit(c)           in_range(c, '0', '9')
#define isxdigit(c)          (isdigit(c) || in_range(c, 'a', 'f') || in_range(c, 'A', 'F'))
#define islower(c)           in_range(c, 'a', 'z')
#define isspace(c)           (c == ' ' || c == '\f' || c == '\n' || c == '\r' || c == '\t' || c == '\v')
#endif


/*
 * Ascii internet address interpretation routine.
 * The value returned is in network order.
 */

/*  */
/* inet_addr */
u32_t inet_addr(const char *cp)
{
        struct in_addr val;

        if (inet_aton(cp, &val)) {
                return (val.s_addr);
        }
        return (INADDR_NONE);
}

/*
 * Check whether "cp" is a valid ascii representation
 * of an Internet address and convert to a binary address.
 * Returns 1 if the address is valid, 0 if not.
 * This replaces inet_addr, the return value from which
 * cannot distinguish between failure and a local broadcast address.
 */
/*  */
/* inet_aton */
s8_t inet_aton(const char *cp, struct in_addr *addr)
{
        u32_t val;
        s32_t base, n;
        char c;
        u32_t parts[4];
        u32_t* pp = parts;

        c = *cp;
        for (;;)
        {
                /*
                 * Collect number up to ``.''.
                 * Values are specified as for C:
                 * 0x=hex, 0=octal, isdigit=decimal.
                 */
                if (!isdigit(c))
                        return (0);
                val = 0;
                base = 10;
                if (c == '0') {
                        c = *++cp;
                        if (c == 'x' || c == 'X')
                                base = 16, c = *++cp;
                        else
                                base = 8;
                }
                for (;;) {
                        if (isdigit(c)) {
                                val = (val * base) + (s16_t)(c - '0');
                                c = *++cp;
                        } else if (base == 16 && isxdigit(c)) {
                                val = (val << 4) |
                                      (s16_t)(c + 10 - (islower(c) ? 'a' : 'A'));
                                c = *++cp;
                        } else
                                break;
                }
                if (c == '.') {
                        /*
                         * Internet format:
                         *  a.b.c.d
                         *  a.b.c   (with c treated as 16 bits)
                         *  a.b (with b treated as 24 bits)
                         */
                        if (pp >= parts + 3)
                                return (0);
                        *pp++ = val;
                        c = *++cp;
                } else
                        break;
        }
        /*
         * Check for trailing characters.
         */
        if (c != '\0' && (!isascii(c) || !isspace(c)))
                return (0);
        /*
         * Concoct the address according to
         * the number of parts specified.
         */
        n = pp - parts + 1;
        switch (n)
        {

        case 0:
                return (0);     /* initial nondigit */

        case 1:             /* a -- 32 bits */
                break;

        case 2:             /* a.b -- 8.24 bits */
                if (val > 0xffffff)
                        return (0);
                val |= parts[0] << 24;
                break;

        case 3:             /* a.b.c -- 8.8.16 bits */
                if (val > 0xffff)
                        return (0);
                val |= (parts[0] << 24) | (parts[1] << 16);
                break;

        case 4:             /* a.b.c.d -- 8.8.8.8 bits */
                if (val > 0xff)
                        return (0);
                val |= (parts[0] << 24) | (parts[1] << 16) | (parts[2] << 8);
                break;
        }
        if (addr)
                addr->s_addr = htonl(val);
        return (1);
}

/* Convert numeric IP address into decimal dotted ASCII representation.
 * returns ptr to static buffer; not reentrant!
 */
char *inet_ntoa(struct in_addr addr)
{
        static char str[16];
        u32_t s_addr = addr.s_addr;
        char inv[3];
        char *rp;
        u8_t *ap;
        u8_t rem;
        u8_t n;
        u8_t i;

        rp = str;
        ap = (u8_t *)&s_addr;
        for (n = 0; n < 4; n++)
        {
                i = 0;
                do {
                        rem = *ap % (u8_t)10;
                        *ap /= (u8_t)10;
                        inv[i++] = '0' + rem;
                } while (*ap);
                while (i--)
                        *rp++ = inv[i];
                *rp++ = '.';
                ap++;
        }
        *--rp = 0;
        return str;
}


//#ifndef BYTE_ORDER
//#error BYTE_ORDER is not defined
//#endif
#ifdef LITTLE_ENDIAN

u16_t htons(u16_t n)
{
        return ((n & 0xff) << 8) | ((n & 0xff00) >> 8);
}

u16_t ntohs(u16_t n)
{
        return htons(n);
}

u32_t htonl(u32_t n)
{
        return ((n & 0xff) << 24) |
               ((n & 0xff00) << 8) |
               ((n & 0xff0000) >> 8) |
               ((n & 0xff000000) >> 24);
}

u32_t ntohl(u32_t n)
{
        return htonl(n);
}

#endif /* BYTE_ORDER == LITTLE_ENDIAN */
